I just tried this and it works and my carpet smells fresh and clean! So much cheaper than store bought stuff! The Retro-Modern Mom: Homemade Carpet Shampoo (Borax washing soap instead of the laundry detergent.
How to Make Homemade Carpet Shampoo or Rug Cleaner
Easy Homemade Carpet Cleaning Solution for Tablespoons Liquid Tide Laundry Detergent cup Awesome cleaner (dollar store brand) 1 scoop Oxyclean (I used generic dollar store brand) 1 teaspoon Downy Fabric Softener (optional) Hot Water, one gallon